Method and apparatus for continuous fabrication of compressor blades



Oct. 2, 1962 E. A. STALKER 3,056,188

METHOD AND APPARATUS FOR CONTINUOUS FABRICATION OF COMPRESSOR BLADES Original Filed Sept. 18, 1952 5 Sheets-Sheet 1 -1 FIG-2 9 29 IN V EN T 0R. EDWARD A.STALKER a ATTORNEYS E. A. S

Oct. 2, 1962 TALKER ATUS FOR CONTINUOUS F COMPRESSOR BLADES 3 Sheets-Sheet 2 mm mm ow r. 0 F- N 7 AV mm Kw m v& V T mm N vm m r 2. E mm mm mm 3 m QR m R M Q-.\ mm kmwm ow v mm NTQI E S DE fl Q nililmhll Kw mw mm n u I I l|\ HHHnn m n Q Q rllllll/lkru I l I I |l r L L L 9 mm on N 0. mm 1v ATTORNEYS Oct. 2, 1962 E. A. STALKER METHOD AND APPAR 3,056,188 ATUS FOR CONTINUOUS FABRICATION OF COMPRESSOR BLADES Original Filed Sept. 18, 1952 5 Sheets-Sheet 3 FIG-15 lllllhllhD FIG-16 llll FIG-14 INVENTOR. EDWARD A. STALKER ATTORNEYS tin United States Patent Ofitice 3,056,188 Patented Oct. 2, 1962 No. 319,183, Sept. 18, 1956, S61. No. 594,269 or. 29-1563) This invention relates to blades for compressors and particularly to stator blades for axial flow compressors.

An object of the invention is to provide a sheet metal blade which is economical to produce.

Another object is to provide a process for producing sheet metal blades which is conducive to use in mass production.

Other objects will appear from the description, drawings and claims.

The above objects are accomplished by the means illustrated in the accompanying drawings in which- FIG. 1 is a side elevation of a blade and base assembly in accordance with the present invention;

FIG. 2 is a top view of the blade and base of FIG. 1;

FIG. 3 is a section along line 3-3 of FIG. 1;

FIG. 4 shows a blade assembly supported in a fragment of a compressor case;

FIG. 5 is a plan view of a blade stem;

FIG. 6 is a schematic view showing the rollers for corrugating the blade stems;

FIG. 7 is an enlarged fragmentary view of the blade showing a groove therein;

FIG. 8 is a schematic view of the machine for producing blades;

FIG. 9 is a detailed end view of the cutter for cutting a groove in the blade strip;

FIG. 10 is a section of a forming die along line Iii-10 of FIG. 8;

FIG. 11 is a section of the same die as in FIG. 10 along line l1-ll1 of HG. 8;

FIG. 12 is a section through another forming die along 12-12 of FIG. 8;

FIG. 13 is a section along line 1313 of FIG. 8 of a third die;

FIG. 14 is a section along line 14-44 of FIG. 8 of a fourth die;

FIG. 15 is a view of the formed blade body stn'p engaged by welding wheels along the trailing edge thereof;

FIG. 16 is a section along line 16-16 of FIG. 8 showing a grinding or cutting wheel in relation to the formed blade body strip;

FIG. 17 is a fragmentary view of a blade body at its aft end enlarged to show the metal removed by the cutter of FIG. 15;

FIG. 18 shows a blade assembly in a fixture for soldering; and

FIG. 19 is a View in perspective of a suitable shear for cutting off the formed strip to the proper lengths.

The sheet metal blade and the process for producing it is directed primarily to blade structures which have a constant chord length and blade section and which are therefore especially suited for stator blades. To reduce the weight of the blades they must be made hollow, but this feature should not unduly increase the cost of fabrication. If the blades require much handwork their cost will be too high. It is possible to reduce the weight and the cost of the blades by the use of sheet metal stampings and a continuous forming operation in the process of this invention where the steps are largely aut0- matic and require very little manual attention. In addition, stator blades require rather sharp trailing edges so that the fiows leaving them have a minimum amount of turbulence to cause vibrations of the rotor blades. Undue amounts of turbulence developed at the trailing edge will reduce the life of the rotating blades because of the induced vibration and fatigue.

Referring to the drawings, a stator blade shown generally at it) according to this invention (FIG. 1), is comprised of a blade body 12 and a blade base 14. The blade body is itself comprised of the skin 15 and the stem 16 within as shown in FIG. 3.

Stem 16 is preferably formed between rollers 17 and 18 (FIG. 6) which indent the flutes 19 defining the splines 2 with the upper center spline having a corrugated surface 21 to effect rigidity as shown in FIGS. 3, 5 and 6.

As shown in FIG. 4 the base serves to mount the blade in grooves 22 provided in a compressor casing 23. Base 14- (FIGS. 1 and 2) is comprised of two upper elements 25 and 26 superimposed on the lower element 23 and fused or bonded thereto at 29. The upper element is made of two separate sheet metal stampings so as to define an opening 3t) of the contour of the root end of the blade when assembled. Since the rear of the opening is very narrow, a punch for cutting the opening 30 from a single piece of metal would have: a short life. By defining the opening by mating elements 25 and 26 together the punch can be very strong and durable since it is necessary to cut only a portion of the opening 30 from each respective part. The blade skin 15 and stem 16 fit into the opening 39 of the base which serves to locate these pieces relative to each other. The sides of the opening are fused as by solder to the blade in sheer making a very strong joint.

The blade body 12 is produced by a continuous process illustrated in FIGS. 8-16. Referring particularly to FIG. 8, a flat metal strip 40 is passed over table portion 42, having suitable guides 4-3 to properly position the sheet as it advances to a cutter wheel 44 which cuts a continuous groove 45 therein. Cutter wheel 44 is mounted on shaft 46 carried by supports 47 mounted on table portion 42 and is driven by a motor (not shown). Where the nose radius of the blade is very small, of the order of magnitude of the blade wall thickness or less, it is necessary to provide this groove along a line on the op posite face of sheet 40 that is to be the leading edge of the blade after forming. When the skin 15 is folded about groove 45, the sides 49 fold closely together, to form a narrow radius in the leading edge, so that they may be readily soldered to fill the groove of reduced width. In the event that a longer nose radius is used the grooving operation may be omitted.

The strip 40 is continuously fed through various fabricating stages of the machine by means of a pair of feed rollers 52 that first direct sheet 40 into a forming die indicated generally at 55. Die 55 is made up of an outer die 56 having a shaped cavity 57 and an inner die 60 having a tongue portion 61 projecting within the cavity. The forming portions of the die parts are spaced apart to receive sheet 40 and are held together at their flanged parts 64 by bolts 65 that in turn secure the die to the bed 68 of the machine. The flat sheet enters die 55 and is gradually bowed until it assumes the generally U-shaped configuration as shown in FIG. 10. As the strip progresses through die 55 the blade is gradually formed into the shape shown in FIG. 11. After leaving die 55 the now partially formed strip enters a second die indicated generally at whereupon the sides 71-72 of the blade are formed into the cross-sectional contour as shown in FIG. 12, with the trailing edges thereof drawn nearer together. Die 75 is constructed similarly to die 55 having an outer die portion 76 and an inner die portion 77 held together by means of the flange portions 78 and bolts 79.

In some instances it is desirable to heat the formed strip before subjecting it to further forming operations. This may be in the form of asuitable heater such as a gas, or induction type, shown diagrammatically by dotted lines at 80. Heater 80 surround the blade strip to be heated as it passes through to effect a more pliable condition of the metal before it enters a third die 85.

Die member 85 is constructed of two parts 87-88 having cavity portions 89 and 90 respectively. The portions 87-88 are secured together by means of bolts 92 and secured to the bed of the machine by bolts 95. As shown in FIG. 13 the blade is formed substantially into its preferred shape as it passes through the opening formed by the die parts. The position of the blade section is defined relative to the die block by the line 108 tangent to the under surface of the blade section.

The strip then passes through a fourth die indicated generally at 105 (FIGS. 8 and 14) which is constructed in the same manner as die 85 except the cross-sectional shape of the die opening 106 of die 105 has its reference axis 107 displaced angularly by the angle 20 from the position of the reference axis 160 of die 85. Thus the strip is twisted by the angle 6 in the space midway between dies 85, 105 as it passes therebetween.

Positioned between dies 85 and 105 is a fusing fixture 110 having an overhanging guide portion 111 to both guide and support the blade strip 40. Carried by a base portion 112, is a pair of welding wheels 115116. The welding wheels receive the trailing edges of the blade port-ions 71-72 therebetween and pass a current through the respective trailing edges as the blade moves between the wheels thus securing the portions 71-72 together in face to face relation and with both edges exteriorly exposed. This may be in the form of a resistance seam weld or a bonding of solder, that is, the strip may have a coating of copper or other solder such as silver solder on one side. The heat from the flow of electric current between the electrode wheels fuses this soldering material. Bonding of the trailing edges fixes the blade body with the proper degree of twist developed by the off-set axis reference lines of the spaced apart dies 85, 105.

Finally the formed strip passes through a cutting or grinding fixture 120 having an overhanging guide portion 121 and a back up portion 122 serving to support the hollow blade body strip 40 as it passes through. Mounted on the fixture is a suitable cutter or grinding wheel 125 which reduces the trailing edge of the strip to a relatively sharp edge, wheel 125 being driven by a motor 126 through a universal connection 127. FIG. 17 shows the trailing edge enlarged to illustrate the material removed by the grinder, such portion being indicated at 128 and shown by cross-hatching. The final operation is to cut the finished formed strip to proper lengths, which may be done by a conventional form of flying saw or shear such as shown in FIG. 19 and well known in the art as for example that shown in Patents 1,936,331, 1,946,926 or 2,079,974, whereupon they are ready to be assembled into the base portion 14. The strip may in addition be pulled through the machine by means of a cable 129 attached to the end thereof.

After the blade bodies are cut to the proper length, each is inserted into the recess 30 of the blade bases. Preferably the corrugated stem 16 is inserted lengthwise of the blade and solder is applied at all the joints where fusing or bonding is required.

The blade assembly is then supported on a fixture 130 (FIG. 18), preferably in an upright position with a weight 131 on the upper end to press the blade body 12 against the base 14 and to properly align it relative thereto. The fixture and its blade assembly are then passed through the furnace to fuse the parts together by the solder. The solder may be in the form of wire like clips placed at the joints or may be powder or filings mixed with a suitable cement (acryloid for instance) and painted on the parts at or near the joints to be soldered. Solder is also placed at the nose groove 45 so that it is filled with fused metal while in the furnace. Preferably the stem 16 is soldered to the skin 15 and to the base 14 at its end although in many instances the solder is omitted from the interior of the skin. The stem even though free from the skin will damp the local vibrations of the skin.

From the above description it can be seen that the forming of the blade body is accomplished by a continuous process whereupon the sheet strip enters at one end of the machine and is operated upon as it progresses through the various stages of the machine and emerges from the opposite end a finished length of hollow blade body stock. The process is continuous and rapid, all operations being performed without the need of individual hand work.

By forming the trailing edges of the skin so that the grinding can be done externally, the economy of the process is greatly advanced and the problem of fitting the sheets together as by scarfing to give an accurate trailing edge is economically and practically solved.

This application is a continuation of copending application Serial No. 310,183, filed September 18, 1952, now abandoned.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. A continuous process for forming hollow sheet metal blades for axial flow compressors and the like which comprises feeding a continuous flat sheet metal strip forwardly, progressively bending said strip during said continuous movement thereof about a line representing the nose of the blade and with a radius less than that of the portions of the blade adjacent the nose into two portions having the general shape of upper and lower faces of a blade respectively, thereafter additionally forming said two portions by bending during said continuous movement thereof to substantially final blade shape including a reverse curve in one of said portions while leaving said portions integrally joined, and welding the trailing edges of the blade strip together with both edges exteriorly exposed to produce a fully formed blade strip adapted to be cut into individual blade lengths.

2. A continuous process for forming hollow sheet metal blades for axial flow compressors and the like which comprises forming a longitudinal groove in a continuously moving fiat strip of sheet metal along a line representing the inner face of the nose of the blade, progressively bending said strip during said continuous movement about said line and with a radius less than that of the portions of the blade adjacent the nose into two portions having the general shape of upper and lower faces of a blade, heating the partially formed moving blade strip to render the material thereof more pliable, additionally forming the moving blade strip to substantially the final blade contour, securing the trailing edges of the blade strip together with both edges exteriorly exposed, twisting said blade strip during said continuous movement to permanently displace the line tangent to the lower surface thereof through a predetermined angle, and intermittently cutting the continuously formed blade strip into individual blade lengths.

3. A continuous proces for forming hollow sheet metal blades for axial flow compressors and the like which comprises feeding a continuous fiat strip of sheet metal, forming a longitudinal groove in said moving strip along a line representing the inner face of the nose of the blade, progressively bending said moving strip about said line and with a radius less than that of the portions of the blade adjacent the nose into the general shape of upper and lower faces of a blade, twisting said blade strip during said continuous movement to permanently displace the line tangent to the lower surface thereof through a predetermined angle, continuously welding the trailing edges of the twisted blade strip together with both edges exteriorly exposed, intermittently cutting the continuously moving formed blade strip into individual blade lengths, inserting corrugated stems within the separated blade lengths, and securing said separated blade lengths with the stems therein in base portions to constitute individual blades.

4. Apparatus for continuously forming hollow sheet metal blades for axial flow compressors and the like which comprises means for feeding a continuous flat strip of sheet metal, means for forming a groove extending longitudinally of said moving strip, dies for receiving said strip from said grooving means and progressively folding the two sides thereof toward each other during the continuous feeding thereof about said groove with a radius less than that of the portions of said blade adjacent said groove to form upper and lower surfaces of a blade with said groove being located on the inner face of the blade nose, means for receiving said blade strip from said dies and for continuously heating the partially formed blade strip during the continuous feeding thereof to render the material thereof more pliable, means for receiving said heated blade strip and additionally forming said blade strip during the continuous feeding thereof to substantially the final blade contour of the upper and lower surfaces, and means for receiving said blade strip from said additional forming means and for continuously securing the trailing edges of the firmly formed blade strip together with both edges exteriorly exposed.

5. Apparatus for continuously forming hollow sheet metal blades for axial flow compressors and the like which comprises means for continuously feeding a fiat strip of sheet metal, means for continuously forming a groove in said moving strip extending longitudinally of said strip, means for receiving said grooved strip during the continuous feeding thereof and progressively folding the two sides thereof toward each other about said groove with a radius less than that of the portions of Said blade adjacent said groove to form upper and lower surfaces of a blade with said groove being located on the inner face of the blade nose, means for thereafter receiving said formed strip during the continuous feeding thereof and twisting the blade strip to permanently displace the line tagent to the lower surface thereof through a predetermined angle, and means for receiving said strip from said twisting means and continuously welding the trailing edges of said twisted blade strip together with both edges exteriorly exposed to retain said twist.

6. A process for forming hollow sheet metal blade strips for subsequent separation into blades for axial flow compressors and the like which comprises continuously feeding a flat sheet metal strip forwardly, continuously passing said strip through forming dies and progressively bending said strip during the continuous movement thereof about a line representing the nose of the blade, and with a radius less than that of the portions of the blade adjacent the nose into two portions having the general shape of upper and lower faces of a blade respectively, passing said strip following said bending through dies during said continuous movement thereof to form said portions to substantially final blade shape including a reverse curve in one of said portions while leaving said portions integrally joined to each other along said line and with the opposite edges free, and thereafter securing said free edges of said formed blade strip together with both edges exteriorly exposed and with said upper and lower faces spaced apart to form said hollow blade strip.

7. A process for forming hollow sheet metal blade strips adapted upon separation to form blades for axial flow compressors and the like which comprises forming a longitudinal groove in a continuously moving flat strip of sheet metal along a line representing the inner face of the nose of the blade, continuously passing said strip through forming dies and progressively bending said strip during said continuous movement thereof about said line with a radius less than that of the portions of the blade adjacent the nose forming two portions having the general shape of the upper and lower faces of a blade, additionally forming said blade strip during said continuous movement thereof by passage through continuous dies to substantially the final blade contour of the upper and lower faces of a blade respectively and with both free edges of the strip exteriorly exposed and located adjacent each other, and permanently securing the free edges of said formed strip to each other during said continuous movement to form the finished blade strip with said free edges defining the trailing edge thereof.

8. A process for forming hollow sheet metal blade strips adapted upon separation to form blades for axial flow compressors and the like which comprises forming longitudinal groove in a continuously moving flat strip of sheet metal along a line representing the inner face of the nose of the blade, progressively bending said strip during said continuous movement thereof about said line with a radius less than that of the portions of the blade adjacent the nose forming two portions having the general shape of the upper and lower faces of a blade, thereafter additionally forming said blade strip during said continuous movement thereof by passage through continuous dies to substantially the final blade contour of the upper and lower faces of a blade respectively and with the free edges of the strip located adjacent each other, twisting the moving blade strip during continuous travel thereof to produce a spanwise twist in said strip, and permanently securing the free edges of said formed strip during said continuous movement thereof to each other with both edges exteriorly exposed to retain said twist and to form the finished blade strip with said free edges defining the trailing edge thereof.

9. Apparatus for forming a continuous hollow sheet metal blade strip adapted for subsequent separation into blades for axial flow compressors and the like which comprises means for continuously feeding a sheet metal strip forwardly, dies for receiving said continuously moving strip and progressively folding the two sides thereof toward each other about a transverse line representing the nose of the blade with a radius less than that of the portions of the blade adjacent the nose to form upper and lower blade surfaces, said dies having surfaces for forming said upper and lower surfaces of said strip as the continuous moving strip passes therethrough to the contour of the upper and lower finished surfaces of a blade leaving said portions integrally joined to each other along said line and with the opposite edges of said strip being free, means for receiving said moving blade strip after it reaches said dies and twisting said blade strip during continuous forward travel thereof to produce a spanwise twist therein, and means for receiving said blade strip from said twisting means and for permanently securing the free edges of said formed blade strip together with both edges exteriorly exposed during said continuous movement to form the trailing edge of the blade strip to retain said spanwise twist therein.

10. Apparatus for forming a continuous hollow sheet metal blade strip adapted for subsequent separation into blades for axial flow compressors and the like which comprises means for continuously feeding a sheet metal strip forwardly, means for forming a longitudinal groove in said moving strip along a line representing the inner face of the nose of the blade, dies for receiving said moving strip from said grooving means and progressively folding the two sides thereof toward each other about said line representing the nose of the blade with a radius less than that of the portions of the blade adjacent the nose to form upper and lower blade surfaces, said dies having surfaces for forming said upper and lower surfaces of said strip to the contour of the upper and lower finished surfaces of a blade leaving said portions integrally joined to each other along said line and With the opposite edges of said strip being free, and means for receiving said strip from said dies and for thereafter securing said free edges of said blade strip together with both edges exteriorly exposed and with said upper and lower faces spaced apart to form said hollow blade strip.

1,313,025 Smith Aug. 12, 1919 8 Wilkinson Nov. 25, Cox July 12, Tiedmann June 24, Peters July 6, Smith May 16, Dalaney Dec. 12, Lampton Dec. 4, Quarnstrom Nov. 25, Daughtery Jan. 118,

FOREIGN PATENTS Great Britain June 16, Great Britain Feb. 9,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,056, 188 October 2, 1962 Edward A. Stalker It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 37, after "forwardly," insert continuously passing said strip through forming dies and line 69, for "proces" read process column 5, line 32 for "firmly" read finally line 48, for "tagent" read tangent Signed and sealed this 5th day of March 1963.,

(SEAL) Attest:

ESTON Ga JOHNSON DAVID L. LADD Attesting Officer Commissioner of Patents 

